An electrode used for a secondary battery is manufactured by coating an electrode current collector with an electrode active material and drying the electrode in a drying furnace. The degree of drying of the coated electrode active material has a close relation with the occurrence of a defect during a process of drying the corresponding electrode, which is performed later.
That is, if the drying is not sufficiently performed, a defect may occur due to contamination and/or separation of the electrode active material while the electrode is being carried in a roll-to-roll manner. On the contrary, if the drying is performed excessively, there is a high possibility of a brittle fracture phenomenon, namely a phenomenon that the electrode is not flexibly deformed but broken due to its brittle feature while being manufactured.
As described above, the dried state of the electrode active material coated on the electrode current collector is an important factor to determine whether a defect occurs in subsequent processes. However, in order to figure out the dried state of the electrode under coating, it is inevitable to stop the operation of the manufacturing equipment at least partially.
In other words, in the existing technique, in order to figure out the dried state of the electrode active material during the electrode manufacturing process, it is necessary that the operation of the equipment is stopped at least partially and then an operator performs diagnosis through visual and touching, thereby deteriorating the overall productivity for the electrode. In addition, since it is difficult to apply a consistent standard in relation to the degree of drying, the quality of the product may not be kept constantly.